The overall objectives of this research are to acquire an understanding of the normal pattern of development in human fetal brain, and a detailed knowledge of some of the mechanisms whereby disordered fetal development occurs. The experimental system is an in vitro system, utilizing human fetal brain in short-term and long-term experiments. Specimens are obtained from hysterotomies, which are performed for the purpose of terminating pregnancies. The goal for the current year is to continue to examine sequential steps in the outgrowth of human fetal cerebral cortex, cerebellar cortex, and hypothalmus in organotypic cultures and in cultures disaggregated with trypsin, utilizing principally morphological techniques.